Fracture features in soda-lime glass after testing with a spherical indenter

A thick soda-lime glass plate was indented with a spherical indenter at high indentation forces up to 1.839 kN. A systematisation of the fracture figures showed a basic structure, consisting of four individual zones. The detailed characteristics of these zones depended on indentation force. Existing models for the assessment of contact diameter and radial and lateral vent cracks length were proven. The appearance of fracture lances was observed and discussed. It was found that these lances formed during the intersection of conchoidal (lateral) fractures, and that their formation was bound to the elastic-plastic period of the indentation process. Features of fracture lances, namely the formation of numerous symmetric lance fronts, periodically occurring lance fronts, lance front statistics, and lance dimensions were described and discussed in detail. It was also shown that the formation of fracture lances showed elements of self-similarity and fractal geometry.